Herein, MOF-derived magnetic CoFe₂O₄ with oxygen vacancy was successfully synthesized to activate peroxymonosulfate (PMS) for the effective degradation of emerging organic contaminants. The introduction of oxygen vacancy not only increased the specific surface area of CoFe₂O₄, but also reduce the charge transfer resistance. The CoFe₂O₄ with oxygen vacancy showed low charge transfer resistance and oxidation potential. Benefitting from the existence of oxygen vacancy, the PMS could be activated quickly by CoFe₂O₄ to produce SO₄^•−. As expected, developed CoFe₂O₄/PMS oxidation system displayed the excellent degradation ability toward various typical organic pollutants, and the organic pollutant could be mineralized into CO₂, H₂O and other inorganic molecules. Interestingly, both redox couples of Fe³⁺/Fe²⁺ and Co³⁺/Co²⁺ played a critical role in the PMS activation process. The SO₄^•−, OH^•, O₂^•− and ¹O₂ were major active species in the CoFe₂O₄/PMS system, which were responsible for the degradation of organic pollutants. Furthermore, proposed CoFe₂O₄/PMS oxidation system also presented a wide pH range of applicability. The existence of magnetic property was convenient for the recovery of catalyst. All in all, this study provided a promising catalyst for the activation of PMS, and obtained results injected some new insights into the research on advanced oxidation processes (AOPs).